This invention relates to fuel controls for turbine types of power plants and particularly to the means for resetting idle speed.
This invention constitutes an improvement over the fuel control idle reset mechanism disclosed in a co-pending application Serial No. 559,458 filed on even date entitled "Fuel Control" by Charles F. Stearns and assigned to the same assignee.
As disclosed in said co-pending U.S. patent application Ser. No. 559,458 the 3-D cam is utilized to control stator vane position and idle speed. It also discloses the concept of utilizing a single cam follower operating off of one profile of the cam to readjust fuel flow. However, in the aforementioned patent application the input to the idle reset operates through the acceleration scheduling linkage through a relatively complex spring and linkage arrangement. Moreover, the output through the linkage operates through a torque summation lever system that controls a pilot valve that establishes a given area ratio for establishing a pressure relationship with its cooperating throttle valve. This invention contemplates simplifying the system described in the aforementioned patent application by applying the idle reset signal directly to the multiplying lever and thereby eliminate the spring and attendant hardware that would otherwise be necessary. The speed lever is operated by a three point lever system so that it responds to the most fuel demand signal and hence preventing reset below flight idle.